Central and Nothern Tucano and Jatobá basins: current exploratlon status

Abstract

Exploration of the Central and Nortnern Tucano and Jatobá basins was resumed in 1986. Based on a review of existent data, three stratigraphic locations were approved and two of these, drilled; a seismic program involving 1500 km of lines also received approval. Seismic data indicate that the Jatobá Basin is relatively shallow, with a pattern of antithetic faults timiting northward-tilting blocks. Data on the Northern Tucano Sub-basin confirm a polarity inversion in this portion of the rift; in other words, the zone of greatest subsidence is located next to the western flank of the though. The basin is characterized by a pattern of NE-trending synthetic faults associated with a second pattern, generally trending NW. The source rock potential of the Candeias Formation has not yet been defined in this basin, but signs of hydrocarbon generation have been observed in the Santa Brigida Formation. The tectonic pattern of the Central Tucano Sub-basin consists of antithetic faults displaying steep vertical throw and generally trending N-S. This sub-basin has tilted sharply N-NE; seismic profiles near the eastern bordar suggest estimated sedimentary thicknesses of over 10 000 m. Well 2-BH·1-BA evidences the good generation conditions of Ilhas Group shales.